The correct answer is: D. Upward compatibility
Upward compatibility is the ability of a newer version of a product to run software or data created for an earlier version of the same product. In the context of operating systems, upward compatibility means that programs designed for earlier versions of the operating system can still be run on the newer version.
Upgradability is the ability of a product to be upgraded to a newer version. This is not the same as upward compatibility, because an upgrade may not be compatible with older versions of the product.
Upward mobility is the ability to move up in social or economic status. This is not the same as upward compatibility, because it does not refer to the ability of a product to be used with older versions of the same product.
Universality is the quality of being applicable to all people or things. This is not the same as upward compatibility, because it does not refer to the ability of a product to be used with older versions of the same product.